TEL AVIV
— Israel's nuclear policy was conceived spontaneously when a young deputy defense minister, Shimon Peres, was confronted by President John F. Kennedy at the White House about the Jewish state's rumored ambitions to become a nuclear power.

Mr. Peres's response – "I can say to you clearly that we shall not introduce atomic weapons into the region. We will certainly not be the first to do so'' – became a tagline repeated for decades to signal the country's self-imposed "no comment" on its reported nuclear capabilities.

This week, Prime Minister Ehud Olmert sought the cover of Peres's now-famous quip after the Israeli leader seemed to inadvertently acknowledge Israel's nuclear weapons – apparently confirming what has been taken granted for decades by much of the world.

In an interview with German television, Mr. Olmert sought to portray Iran as reckless while placing Israel alongside the accepted nuclear powers. "Iran openly, explicitly, and publicly threatens to wipe Israel off the map," Olmert said while visiting Germany. "Can you say that this is the same level, when you are aspiring to have nuclear weapons, as America, France, Israel, and Russia?"

The uproar that ensued in Israel and abroad highlights the fragility of one of Israel's most finely tuned defense policies, a doctrine of nuclear ambiguity that has enabled Israel to deter foes for decades in a region with only one alleged nuclear power.

But as the possibility of a nuclear Iran looms, some are arguing that Israel may need to rethink that very policy.

"The ambiguity so far has been useful, and we have never threatened the region with a nuclear catastrophe. But sometimes there is no way out of it," says Shlomo Aronson, a political science professor at Hebrew University. "When [Iranian President Mahmoud] Ahmadinejad talks about wiping Israel off the map, this may mean the end of Iran, too.''

To be sure, Olmert's aides were quick to deny that the prime minister meant to blow open the tight-lipped policy of four decades. Critics back home, however, were quick to assail the prime minister for what they called a reckless verbal slip. Most commentators, meanwhile, defended the longstanding doctrine.

"It has been the right policy; it has helped Israel. The Arabs, knowing that Israel is a nuclear superpower and a conventional weapons superpower, probably reduced their aspirations or limited their plans" to attack Israel, says Yossi Melman, an Israeli journalist and historian who cowrote a forthcoming book on Iran's nuclear program. Disclosure would spur "pressure on Israel from the international community."

The policy was formalized in 1970 between then-Israeli Prime Minister Golda Meir and President Richard Nixon, who agreed to accept Israel's nuclear status on condition that it observe a rigorous vow of silence. In order not to disrupt the US drive to gain nonproliferation commitments from other countries, Israel committed to remain mum about its nuclear program, to avoid tests, and not to threaten other countries with attack.

Israel's nuclear deterrent is credited by analysts with convincing Egyptian President Anwar Sadat to abandon hopes of a military defeat of Israel, and with dissuading Iraqi President Saddam Hussein from fitting the Scuds he fired at Israel in the 1991 Gulf War with nonconventional warheads.

Meanwhile, the low profile has allowed Israel to skirt any internationally imposed nuclear oversight while avoiding stirring a nuclear race with its immediate neighbors.

"Breaking the ambiguity now will create two undesirable results," wrote Ron Ben Yishai, a defense commentator, for the Israeli website Ynet. "One would be to provide an excuse for Israel's neighbors to [acquire nonconventional materials], and [the other would be] to bolster efforts in the international arena to dismantle Israel of its nuclear capability."

Indeed, an Arab League spokesman insisted the comment was an intentional "test balloon" and urged member states to bolster their readiness for a nuclear attack, the Egyptian official news agency reported. For years, Egypt has made occasional calls for the international community to force Israel to open up its nuclear program to inspection.

For decades, discussion of its nuclear policy has been something of a taboo in Israel. Academic research and media articles are subject to a military censor, and information on Israel's nuclear program is usually attributed to "foreign sources" for safe measure.

The only inside documentation of the program was made public in the 1980s by Mordechai Vanunu, a former employee at Israel's Dimona Nuclear reactor who gave pictures of the core to the London Sunday Times, a report which spurred a round of speculation about the size of Israel's nuclear arsenal.

Some in Israel have questioned whether stifling discussion of the country's most important weapon is healthy for a democracy. But defenders of the policy insist that silence is the most responsible approach Israel can take.

"This is viewed as something that is obviously not for use unless Israel faces an extreme situation where it feels its existence is threatened," says Emily Landau, a fellow at the Tel Aviv University affiliate Institute of National Security Studies. "The international community should be happy that Israel's policy is a policy of ambiguity."

But an atomic Iran would require a change in Israel's longstanding policy, say some experts. A region with more than one potential atomic power calls for a more explicit form of deterrence.

"In order to make a situation that existed in the cold war, that existed between the US and Soviet Union, you need that both sides threatened by each other," says Michael Karpin, an author of a history of Israel's nuclear program, "otherwise the side that doesn't make the threat is weaker. For a balance of terror so that both sides don't use the bomb, you need to know that the other side has the bomb."